1. Field of the Invention
The present invention relates to fibre channel network switches. More specifically, the present invention relates to methods and apparatus for implementing high availability for a fibre channel switch in a storage area network. High availability includes services such as mirroring, logging, persistence, application reinitialization, and switchover.
2. Description of Related Art
Very limited high availability services exist in fibre channel networks. One form of high availability for fibre channel storage area networks is route redundancy. When a first storage area network entity, such as a server, attempts to send a message to a second storage area network entity, such as a disk array in a fibre channel fabric, the message passes through various switches in the fibre channel fabric. If a particular switch fails, neighboring switches can recognize the failure and pass the message along alternative routes. The alternative routes can bypass the failed switch to maintain network operation. However, it may not always be possible to bypass the failed switch. In one example, the failed switch may be directly connected to the target disk array and there may be no alternative routes to the destination. Bypassing the failed switch can also be disruptive to the operation of the fibre channel network. Traffic may be slowed through switches that now have to carry additional traffic. Overall bandwidth of the fabric can decrease.
Many other high availability services fail to preserve state information, causing slow network operation or reinitialization of applications.
It is therefore desirable to provide methods and apparatus for providing high availability in a fibre channel switch and improving high availability services with respect to some or all of the limitations noted above.